Field
The present disclosure relates generally to a display apparatus capable of wirelessly receiving power, and for example, to a display apparatus and a control method thereof, in which the amount of power to be wirelessly transferred is temporarily decreased to protect a user if the user comes within a predetermined range while wirelessly receiving power.
Description of Related Art
With development of information technology (IT), many technologies have been proposed to supply power to various electronic products. In particular, a wireless power transmission technology has been developed and used for wirelessly supplying power without physical contact between devices as opposed to the existing electronic devices of using a wire to receive electric energy or power. The electronic device capable of wirelessly receiving power may operate with the received power.
By the wireless power transmission technology, power supply is possible anywhere and anytime without using a power line such as an electric wire. Thus, it is expected that the wireless power transmission technology combines with various industrial fields such as wireless charging for a mobile device, wireless power supply for home appliances, charging for electric vehicles, a wireless sensor for Internet-of-things IOT), etc. and promotes innovation for future society.
As a method of wirelessly supplying power, there are a magnetic induction method, a magnetic resonance method and an electromagnetic-wave method. The Wireless Power Consortium has released the standards for the wireless power transmission technology using the magnetic induction method among the above methods. The standards of the Wireless Power Consortium specify the method of transmitting power by the magnetic induction method.
However, a strong magnetic field may be generated in the vicinity of a power supplying apparatus and a power receiving apparatus during wireless transmission of the power, and may be harmful to a user if s/he gets too close to it. In this regard, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has determined and notified an allowable exposure limit to electromagnetic waves from products in order to protect a human body from non-ionizing radiation, and this allowable exposure limit has been used as recommended standards or general international standards. Based on the ICNIRP standards, the public is restricted to be exposed to an electric field of 8.3*10−2 (kV/m), a magnetic field of 21(A/m) and a magnetic flux density of 2.7*10−5(T) for about 6 minutes since a frequency band of 200˜300 KHz is used in the wireless power transmission. The ICNIRP has established the exposure limits for the public, who does not realize and takes no measure to the exposure to electromagnetic fields, more strictly than those for workers, who typically recognize the exposure of electromagnetic waves and are aware of potential risks.
The exposure to the electromagnetic waves has been restricted for a human body all over the world, and therefore users of a display apparatus wirelessly receiving power to display an image also need to be protected from electromagnetic waves radiated between the wireless power supplying apparatus and the wireless power receiving apparatus.
Conventionally, a wireless power transmission side has measured a distance from a user in order to protect him/her or has ceased transmitting the power if a user comes between the transmitting side and a receiving side. Thus, there is a problem that a user is not effectively protected since the receiving side does not offer any information and only the transmitting side performs unilateral determination and control.